1. Field of the Invention
The invention relates to a motor structure, in particular, to a thin motor structure.
2. Description of the Related Art
Recently, electrical products tend to be small size and thin. For example, notebook computers are getting thinner and thinner. To meet the demand of thin electrical products, a thin fan motor structure must be obtained.
In developing a thin motor structure, the most important problem is that the stator structure of the conventional motor cannot meet the demands of the designer, and there are difficulties in manufacturing a thin conventional stator structure.
FIG. 1 is a partial cross-sectional view showing a conventional motor structure. FIG. 2 is a front view showing the motor structure as shown in FIG. 1. Referring to FIGS. 1 and 2, the motor structure includes a magnet ring 100 and a stator 200. The magnet ring 100 is a part of a rotor (not completely shown). The stator 200 includes a silicon steel sheet set 201 with four poles and a coil (wirings) 202 of the silicon steel sheet set 201.
Since the silicon steel sheet set 201 is composed of a plurality of silicon steel sheets stacked together, the edges of the silicon steel sheet set 201 are sharp. Therefore, a film or cover (not shown) is needed to cover the silicon steel sheet 201 for winding the wirings 202 without damaging them.
In the above-mentioned motor structure, the method of winding the coil wastes a lot of space, that is, the coil cannot totally fill the circular area surrounded by the silicon steel sheet set 201, deteriorating the performance of the motor.
In order to make the above-mentioned motor structure thin, there may occur the following effects:
(a) since the number of the silicon steel sheets must be relatively small and the space for the winding is not sufficient, the motor performance is relatively poor;
(b) since the size of the stator is relatively small and the tolerance is relatively strict, the difficulty level is increased in manufacturing and assembling the motor; and
(c) since the edges of the silicon steel sheet set of a thin stator are relatively sharp, the wirings wound thereon are easily damaged and short-circuit the coil.
In general, the stability of the operating motor improves as the number of poles for the motor increases. In the above-mentioned motor structure, the number of poles thereof is four. If the number of poles is increased to eight, undesirable effects occur. For example, difficulty in winding the wiring may occur. Also in a condition that seldom occurs, the motor may easily short out or the performance thereof will be poor.
It is therefore an object of the invention to provide a thin motor structure capable of improving the performance of the motor and facilitating the manufacturing processes.
According to one aspect of the invention, a motor structure includes a stator having a coil assembly, and a rotor having a circular magnet located above the coil. The stator includes a coil assembly having a ring-shaped slot, a plurality of first teeth, a plurality of second teeth, and a coil. The ring-shaped slot has an inner periphery on its inner side and an outer periphery on its outer side away from the inner periphery. The plurality of first teeth is mounted around the inner periphery of the ring-shaped slot. The plurality of second teeth is mounted around the outer periphery of the ring-shaped slot. The coil is wound in the ring-shaped slot.
The above-mentioned motor structure may further include a base. The coil assembly is mounted on the base. In addition, a ring-shaped concavity may be formed on the base for the coil assembly to be mounted therein.
Furthermore, the stator may further include a static shaft substantially perpendicular to, and fixed on the base. In this case, a ring-shaped groove may be formed around the static shaft. Alternatively, the rotor may further include a hub in which a through hole is formed, a metal sheet arranged between the hub and the circular magnet, and a bearing positioned in the through hole and being penetrated by the static shaft. Moreover, the motor structure may further include an engagement ring positioned in the through hole and on the bearing for fixing the bearing, and an elastic ring positioned in the ring-shaped groove for elastically fixing the bearing.